1. Field of the Invention
The present invention generally relates to plumbing devices and, more particularly, to an improved device for temporarily plugging drain pipes in order to test the same.
2. Prior Art
When a new home, condominium or apartment house or the like is constructed,the drains must be tested for leaks before they can be approved by an inspector. This is usually accomplished by first inserting a temporary plug device through the clean-out pipe located outside the structure to a point where it intersects a sewer line running from the structure drain to the main sewer line. Such plug device usually is an elongated hollow expansible sausage-like unit which has a nipple at one end through which air or water is introduced into the unit until the unit expands sufficiently so that one end blocks the clean-out pipe while the other end of the device seals off the sewer line. Water can then be introduced into the entire house drain and sewer system to check for leaks.
Such a conventional plug device has several drawbacks. Thus, the device is usually difficult to slide into place and to retrieve due to its shape. Moreover, when the device is deflated, the fluid from the house drains not only flows into the sewer line but also backs up through the clean-out pipe, especially in multi-story structures, creating a sanitation hazard. Moreover, the device usually is adapted for use only with one diameter of pipes, necessitating various different sizes of the device to use in various plumbing systems. In addition, if the device is subjected to excess pressure during use, it will rupture, with possible serious injury to workmen and the plumbing and sewage system.
Accordingly, there is a need for an improved type of drain pipe plug device which can be inflated with either a liquid or a gas, and is safe to use. Such device should be easy to insert and retrieve, should not rupture even when subjected to excess inflation, pressure, and should be adaptable to various drain pipe diameters. Of more importance, the device should prevent, upon its deflation after the drain test is run, back-flow of fluid from the house drains into the clean-out pipe.
A drain pipe plug device has been devised which satisfies most of the foregoing needs and is set forth in U.S. Pat. No. 4,660,603, issued to George Tash, the inventor of the present invention. The drain pipe plug device of U.S. Pat. No. 4,660,603 employs a resilient, flexible, elongated member of rubber or the like having a front outlet portion, a rear inlet portion and a particularly flexible middle portion of reduced diameter. The sidewall of the outlet portion is thicker than that of the inlet portion so that the outlet portion collapses first during deflation of the device from its expanded blocking state in a drain pipe, assuring that fluid from the house drain into which it has been inserted passes out the sewer line, not back up the clean-out pipe. However, the relative thicknesses of the outlet portion and the inlet portion must be carefully controlled during manufacture of the device in order to achieve the desired results. This requires careful monitoring of the tolerances of the mold configuration in which the device is made, an expensive procedure.
Accordingly, there remains a need for an improved drain pipe plug device which can be manufactured more easily and less expensively than the aforesaid patented device and which provides all the advantages of that device.